Performance of a day/night water heat storage system for heating and cooling of semi-closed greenhouses in mild winter climate

A novel system for heating/cooling greenhouses based on air/water heat exchangers connected to a thermally stratified water storage tank was tested in a small greenhouse compartment at the Experimental Station of the Cajamar Foundation in Almería, Spain. The system maintained a closed greenhouse (no natural ventilation) throughout the winter and spring during which a truss tomato crop was grown. Atmospheric CO2 concentration could be maintained during the daytime allowing for greater net photosynthesis in relation to a reference greenhouse in which traditional natural ventilation was used to control temperature and humidity. Three fine wire heat exchangers (Fiwihex®) were installed 1 m above the crop when at full development. The heat exchangers allowed for a very efficient transfer of the sensible and latent heat accumulated in the compartment. During the winter, the daytime temperatures were maintained below the ventilation set point (30°C). During the night, the system was able to maintain temperatures above the heating set point (12°C), with stored warm water temperatures between 15 and 17°C after clear days. After cloudy days, with water temperatures between 11 and 13°C, the system could always keep a temperature gradient with the exterior of 4-6°C, enough to maintain greenhouse air temperatures above 8°C the entire night. When seasonal night air temperatures exceeded the heating set point, the hot water at the top of the tank was cooled to the wet bulb temperature by means of an open cooling tower. The cooled water was used for cooling the greenhouse, which allowed for closing the greenhouse for a longer period. The water condensate during the cooling mode, allowed for a high water saving and maintained the relative humidity very constant during the day (around 80%). During the night, humidity was kept at 90% without ever reaching saturation

Horticultural Production System of the Province of Almería

En este trabajo se realiza una exhaustiva descripci&oacute;n de la horticultura de invernadero, fruto del inter&eacute;s de la Consejer&iacute;a de Agricultura, Pesca y Desarrollo Rural de la Junta de Andaluc&iacute;a por conocer la evoluci&oacute;n tecnol&oacute;gica del sector hort&iacute;cola de Almer&iacute;a. Gracias a la colaboraci&oacute;n de la Fundaci&oacute;n Cajamar y a estudios similares promovidos con anterioridad por ambas instituciones, se ha logrado documentar la evoluci&oacute;n y tendencias tecnol&oacute;gicas m&aacute;s recientes del sistema de producci&oacute;n de hort&iacute;colas protegidos de la provincia de Almer&iacute;a. Esta publicaci&oacute;n forma parte del proyecto &lsquo;TRANSFORMA-Desarrollo sostenible en cultivos hort&iacute;colas protegidos&rsquo;, que viene ejecutando el Instituto de Investigaci&oacute;n y Formaci&oacute;n Agraria, Pesquera y de la Producci&oacute;n Ecol&oacute;gica, como herramienta de transferencia de conocimiento y tecnolog&iacute;a a los profesionales del sector. La publicaci&oacute;n se estructura en cinco cap&iacute;tulos. El primero, que introduce el proceso de elaboraci&oacute;n y la metodolog&iacute;a empleada en este estudio, el segundo trata la caracterizaci&oacute;n de las explotaciones hort&iacute;colas y sus titulares. Los temas relativos al invernadero son desarrollados en el tercer cap&iacute;tulo, incluido el equipamiento para el control de clima y el riego. En el cuarto, quedan reflejados los medios de protecci&oacute;n de cultivos, la mano de obra y la maquinaria y por &uacute;ltimo, se analizan los cultivos hort&iacute;colas representativos del sistema productivo de invernadero de la provincia.</p